Fatigue Life Assessment of Steel Pressure Vessels with Varying Stress Concentration, Residual Stress, and Initial Cracks.

This paper presents the fatigue life assessment procedure for the welded joint of ship structure. Test model is a boxing fillet specimen, the idealized welded joint model of longitudinal and transverse members in ship structure. Fatigue test was executed according to the 14-points S-N method of JSME, and experimental data were presented in the S-N curve based on HSS (Hot Spot Stress) approach. To define the fatigue life of crack initiation and crack propagation, S-N data for each length of crack were appraised. In this study, the new FE analysis algorithms for the estimation of residual stress relaxation due to external load and residual stress redistribution due to crack propagation were proposed to assess the effect of residual stresses on crack growth precisely. Initial welding residual stress field was obtained by thermal elasto-plastic analysis considering temperature dependent material properties, and the amount of residual stress relaxation and redistribution were assessed by subsequent elasto-plastic analysis. In the analysis of crack propagation, the SIF (Stress Intensity Factor) range was evaluated by 1/4-point displacement extrapolation method, and the effect of welding residual stresses on fatigue behaviors was considered by introducing the effective SIF concept. The test results of crack propagations were compared with the predicted data from the analysis.

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Automated Fatigue Life Assessment for Welded Cruciform Joint Considering Welding Residual Stress

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.2800 ◽

2005 ◽

Vol 297-300 ◽

pp. 2800-2805

Author(s):

Tak Kee Lee ◽

Chae Whan Rim ◽

Seung Ho Han ◽

Jong Han Lee

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Stress Distribution ◽

Rational Design ◽

Welding Residual Stress ◽

Life Assessment ◽

Assessment Process ◽

Automated System ◽

Fatigue Life Assessment ◽

Cruciform Joint

For a rational design of a welded joint, it is necessary to repeatedly assess the fatigue life of the joint with various dimensions and welding conditions. In this paper, an automated, repeatable/repetitive fatigue life assessment process for a welded cruciform joint was studied. The process consists of a structural analysis to obtain the stress distribution in the vicinity of the weldtoe, a thermal elasto-plastic analysis to determine the welding residual stress, and a fatigue life assessment based on the analyzed stress distribution and welding residual stress. With changes in design conditions including dimensions and/or welding heat input, the aforementioned tasks have to be performed. Using a commercial tool for system integration, automation of a repeated process for a welded cruciform joint based on 2D modeling was achieved. In this automated system, data exchanges between programs, regardless of whether they are commercial or in-house, work well, and parametric studies for optimal design can be performed.

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Measurement of Residual Stress Distribution and Fatigue Life Assessment of Similar and Dissimilar Butt-Welded Joint

Lecture Notes in Mechanical Engineering - Proceedings of Fatigue, Durability and Fracture Mechanics ◽

10.1007/978-981-10-6002-1_35 ◽

2017 ◽

pp. 433-443

Author(s):

Varun Ravichandran ◽

E. R. Revanth ◽

D. Varun Kumar ◽

M. Sandeep ◽

A. Harish

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Stress Distribution ◽

Welded Joint ◽

Residual Stress Distribution ◽

Life Assessment ◽

Fatigue Life Assessment

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Fatigue-Life Assessment

10.31399/asm.hb.v11a.a0006819 ◽

2021 ◽

pp. 98-133

Author(s):

Phillip E. Prueter

Keyword(s):

Fatigue Life ◽

Damage Tolerance ◽

Pressure Vessels ◽

Life Assessment ◽

Cyclic Plasticity ◽

Fatigue Assessment ◽

Fatigue Life Assessment ◽

Component Design ◽

Engineering Mechanics ◽

Growth Approach

Abstract This article offers an overview of fatigue fundamentals, common fatigue terminology, and examples of damage morphology. It presents a summary of relevant engineering mechanics, cyclic plasticity principles, and perspective on the modern design by analysis (DBA) techniques. The article reviews fatigue assessment methods incorporated in international design and post construction codes and standards, with special emphasis on evaluating welds. Specifically, the stress-life approach, the strain-life approach, and the fracture mechanics (crack growth) approach are described. An overview of high-cycle welded fatigue methods, cycle-counting techniques, and a discussion on ratcheting are also offered. A historical synopsis of fatigue technology advancements and commentary on component design and fabrication strategies to mitigate fatigue damage and improve damage tolerance are provided. Finally, the article presents practical fatigue assessment case studies of in-service equipment (pressure vessels) that employ DBA methods.

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